Reclosable food package

ABSTRACT

The invention relates to a reclosable package  10  which includes a rigid base member  11 , a product  50  placed over said rigid base member, a cover film  13  laid over product  50  and sealed to rigid base member  11  wherein removable reclosure means  14  ( 114 ) are embedded in rigid base member  11  and cover film  13  is also sealed to removable reclosure means  14  ( 114 ). Also disclosed are a rigid base member  11  having removable reclosure means  14  ( 114 ) embedded therein and a method of making the reclosable package  10.

This application is a continuation of U.S. patent application Ser. No.11/258,430, filed Oct. 25, 2005, which claims the benefit of Europeanpatent application serial no. 04105308.3 filed on Oct. 26, 2004.

FIELD OF THE INVENTION

The present invention relates to the field of reclosable food packages,particularly packages having a rigid base and a flexible cover sealedonto the rigid base.

BACKGROUND OF THE INVENTION

Hermetically sealed rigid containers, such as trays with a flexible lidsealed around their edges, are widely used in the packaging of foodproducts. This type of packaging offers several advantages: the rigidityof the container provides protection to the contents of the packageduring transportation, storage and handling, and the hermeticity of theseals contributes to the increase in the shelf-life of the product.Reclosable packages are convenient for a variety of reasons. For examplewhen the packaged product is not immediately consumed after opening ofthe package, it could undergo contamination and spoilage thereforeforcing the consumer to time-consuming repackaging operations.

Several attempts have been made in the past to provide reclosable rigidpackages. For instance U.S. Pat. No. 5,651,462 discloses a packagingcomprising a tray and a flexible cover which is permanently sealed tothe tray flange except at one edge where a reclosable interlocking sealis placed. Said interlocking seal includes a male closure profile and afemale closure profile. In one embodiment the female closure profile hasbeen incorporated into the flange of the tray, while the male closureprofile is a separate piece which has been attached to the cover. Inthis proposal, the need to assemble separate components, such as themale profile, adds complexity and cost to the final package. Thereforethere is still the need to provide a reclosable rigid package that doesnot require a number of separate steps to be manufactured.

A first objective of the present invention is a simple and easy to usereclosable package. Another objective is a rigid base member suitable toobtain a reclosable package which is simple to make. Still anotherobjective of the present invention is a method of making a reclosablepackage that does not require additional steps with respect to themethod for making a non-reclosable package.

SUMMARY OF THE INVENTION

A first object of the present invention is therefore a reclosablepackage comprising a rigid base member, a product placed on the rigidbase member and a cover film placed over the product and sealed to therigid base member all around said product, characterized in thatremovable reclosure means are embedded in the rigid base member and thecover film is secured to the removable reclosure means.

A second object of the present invention is a rigid base member havingremovable reclosure means embedded therein suitable to obtain areclosable package of the first object.

A further object is a method of making a reclosable package according tothe first object of the invention. These and other objects, advantages,and features of the invention will be more readily understood andappreciated by reference to the detailed description of the inventionand the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B respectively show a perspective and a sectional view ofa reclosable package according to one embodiment of the presentinvention in the closed state;

FIGS. 2A and 2B show two further embodiments of the reclosable packageof the present invention in the closed state;

FIGS. 3A and 3B respectively show a perspective and a sectional view ofa reclosable package according to one embodiment of the presentinvention in the open state.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A and 1B represent a reclosable package 10 according to oneembodiment of the present invention. Reclosable package 10 comprises arigid base member 11 and a product 50 placed on rigid base member 11. Asused herein, the term “rigid” refers to a material that does not deform,bend or loose its shape when deprived of support. Rigid base member 11comprises removable reclosure means 14 which are embedded in the rigidbase. Preferably they are located around the periphery of rigid basemember 11. Cover film 13 is placed over product 50 and it is sealed torigid base member 11 along its periphery and all around product 50 bymeans of seal 16. Cover film 13 is also secured to removable reclosuremeans 14 by means of bond 12. Rigid base member 11 is shown in FIGS. 1Aand 1B in the form of a tray with a bottom wall 21 and four upwardlyprojecting side-walls 22 terminating with a peripheral flange 23,horizontally extending from the side-walls 22. Alternatively, rigid basemember 11 can be in the form of a flat, dish-like support, as shown inFIGS. 2A and 2B. Rigid base member 11 can have a rectangular shape, asshown in the figures, or it can have any other suitable shape, such asround, square, elliptical etc.

Rigid base member 11 is made of a single layer or, preferably, of amulti-layer polymeric material. In case of a single layer materialsuitable polymers are for instance polystyrene, polypropylene,polyesters, high density polyethylene, poly(lactic acid), PVC and thelike, either foamed or solid. Generally, rigid base member 11 is made ofa multi-layer material. Suitable polymers are for instance ethylenehomo- and co-polymers, propylene homo- and co-polymers, polyamides,polystyrene, polyesters, poly(lactic acid), PVC and the like. Part ofthe multi-layer material can be solid and part can be foamed. Preferablyrigid base member 11 comprises at least one layer of a foamed polymericmaterial chosen from the group consisting of polystyrene, polypropylene,polyesters and the like. The multi-layer material can be produced eitherby coextrusion of all the layers using well-known coextrusion techniquesor by glue- or heat-lamination of, for instance, a rigid foamed or solidsubstrate with a thin film. The thin film can be laminated either on theside of rigid base member 11 in contact with the product or on the sidefacing away from the product or on both sides. In the latter case thefilms laminated on the two sides of rigid base member 11 can be the sameor different. A layer of an oxygen barrier material, for instance(ethylene-co-vinyl alcohol) copolymer, is optionally present to increasethe shelf-life of product 50. In a preferred embodiment rigid basemember 11 is obtained from a sheet of foamed polymeric material having afilm comprising at least one oxygen barrier layer and at least onesurface sealing layer laminated onto the side facing product 50, so thatthe surface sealing layer of the film is the food contact layer of rigidbase member 11. A second film, either barrier or non-barrier, can belaminated on the outer surface of rigid base member 11. Rigid basemember 11 typically has a thickness in the range from 1 to 15 mm,preferably from 2 to 10 mm, and even more preferably from 3 to 9 mm.Rigid base member 11 is manufactured through common techniques such asthermoforming or injection moulding.

When reclosable package 10 is in the closed state removable reclosuremeans 14 are embedded in rigid base member 11. The term “embedded” isused herein to indicate that removable reclosure means 14 fit tightlyinto the complementary housings 17 present in rigid base member 11 insuch a way that reclosure means 14 do not exceed the height of rigidbase member 11. Removable reclosure means 14 are generally located atthe periphery of rigid base member 11. In the case of a tray-like basemember 11, such as the one shown in FIGS. 1A and 1B, removable reclosuremeans 14 are positioned in the flange area 23.

Removable reclosure means 14 can be either one or more than one discreteelements having different sizes and cross-sections. For instance, in thepackage of the invention shown in FIG. 1A and 1B, four removablereclosure means 14, having a circular cross-section, are positioned atthe corners of flange 23 of rigid base member 11. Alternativeembodiments of the reclosable package of the invention are shown inFIGS. 2A and 2B.

FIG. 2A shows a reclosable package 10 having a flat rigid base member 11and one single removable reclosure mean 14, having a rectangularcross-section, positioned parallel to one of the edges of rigid basemember 11.

FIG. 2B shows a reclosable package 10 having a flat rigid base member 11and one removable reclosure mean 14 forming a continuous framesurrounding the product.

Removable reclosure means 14 are rigid elements preferably made ofthermoplastic materials. Alternatively they can be made of any othermaterial which is compatible with the overall package, such ascardboard, rubber, metal and the like. According to one preferredembodiment when the removable reclosure means 14 are made of athermoplastic material any plastic material can be suitably employedsuch as polyolefins, rubbers, polyamides, polyesters, PVC and the like.They can be made of a material different from the one used for the rigidbase member or, preferably, of the same material as rigid base member11. Even more preferably removable reclosure means 14 are made of thesame material as rigid base member 11 and are created by cutting rigidbase member 11 during its manufacturing cycle in the right size andshape to give removable reclosure means 14. Removable reclosure means 14can be cut from rigid base member 11 by using a laser beam, by means ofknives or by any other suitable method known in the art. The cutting cantake place at any stage of the rigid base member manufacturing cycle.The cutting of removable reclosure means 14 from rigid base member 11can be complete, that is removable reclosure means 14 are totallyseparated from rigid base member 11 so that they are held in place,embedded in base member 11, only by friction. Alternatively, the cut canbe partial either around the perimeter of removable reclosure means 14,or along its height, therefore reducing to a minimum the risk of losingremovable reclosure means 14 from rigid base member 11 during thedistribution step.

With respect to other solutions reclosable package 10 offers severaladvantages: firstly it eliminates the need of separately producing rigidbase member 11 and removable reclosure means 14, secondly it eliminatesthe need of joining the two elements therefore reducing the number ofoperations to be carried out either by the rigid base member supplier orbefore the packaging operations take place.

Cover film 13, generally in sheet or web form, may be a single layer ora multi-layer structure. In the latter case the various layers may bebonded together by any conventional and suitable method, e.g.coextrusion, extrusion coating, lamination etc. In case of a singlelayer structure suitable polymeric materials are for instancepolyolefins, such as ethylene homo- and co-polymers and propylene homo-and co-polymers, ionomers, polyamides, polyesters, polystyrene,poly(lactic acid) and the like. In case of a multi-layer structuresuitable materials for the layer that will be sealed to the rigid basemember 11 (the heat-sealable layer) are as indicated above. Cover film13 can be either oriented or non-oriented and in the former case it canbe either heat-shrinkable or non heat-shrinkable. Generally, cover film13 has a thickness comprised between 10 and 100 μm, preferably from 15to 75 μm and even more preferably from 20 to 60 μm. In one embodiment ofthe present invention, when the base member 11 has a limited gastransmission rate, cover film 13 preferably comprises one heat-sealablesurface layer facing product 50, one oxygen barrier layer and optionallyone outer heat-resistant layer, wherein the outer heat-resistant layeris made, for instance, from materials chosen from the group ofpolyolefins, polyesters and polyamides.

Cover film 13 is sealed to rigid base member 11 by means of seal 16,which runs along the periphery of rigid base member 11 encirclingproduct 50. Seal 16 can be positioned either inward or outward of theremovable reclosure means 14 with respect to product 50. When seal 16 ispositioned inward of removable reclosure means 14, as shown in FIG. 1A,ingress of air into reclosable package 10 can be more efficientlyprevented. Cover film 13 is secured to removable reclosure means 14 bymeans of bond 12. Alternatively, seal 16 and bond 12 can partiallycoincide, thus reducing the part of rigid base member 11 taken up by theseals.

Cover film 13 can be secured to rigid base member 11 either at the sametime or at a different time, either before or after, it is secured toremovable reclosure means 14. Typically, cover film 13 is heat-sealed tobase member 11, preferably by means of a peelable seal, that is a sealthat can be manually pulled open by the consumer without damaging eithercover film 13 or rigid base member 11. Cover film 13 is secured toremovable reclosure means 14 by sealing, welding, glueing, stitching orby any other suitable mean known in the art. Generally, cover film 13 isheat-sealed to reclosure means 14, preferably by means of a permanentheat-seal, that is a seal that cannot be opened without causing thedestruction of at least one of the materials joined by the seal.

A second object of the present invention is a rigid base member 11having removable reclosure means 14 embedded therein suitable for makingthe reclosable package of the first object of the invention.

A third object of the present invention is a method of making areclosable package 10, comprising the steps of:

-   -   providing rigid base member 11 with removable reclosure means 14        embedded therein;    -   placing product 50 over rigid base member 11;    -   laying cover film 13 over product 50;    -   optionally evacuating and/or gas flushing the space between        rigid base member 11 and cover film 13 with a suitable gas or        gas mixture; and    -   securing cover film 13 to base member 11 around product 50 and        to removable reclosure means 14.

Depending on the nature of the product to be packaged it may bedesirable to modify the atmosphere inside reclosable package 10 beforecover film 13 is heat-sealed to rigid base member 11. The atmosphere canbe modified either by simply flushing with a suitable gas or gas mixtureor by firstly evacuating and then back-filling with a suitable gas orgas mixture the space between rigid base member 11 and cover film 13.The gas or the gas mixture are selected to maximize the shelf-life ofproduct 50. Preferred gases to replace evacuated air include oxygen,carbon dioxide, nitrogen, argon and mixtures thereof. Once this step hasbeen completed, cover film 13 is then secured to both rigid base member11 and to removable reclosure means 14. Preferably cover film 13 will beheat-sealed to rigid base member 11 forming a peelable seal 16encircling product 50 and it will be permanently secured to removablereclosure means 14 by means of bond 12. The two operations can becarried out either at the same time or at different times. The differentstrength with which cover film 13 is bonded to rigid base member 11 andto removable reclosure means 14 can be obtained in several ways. Whenrigid base member 11 and removable reclosure means 14 are made of thesame material seals 16 and 12 could be made using different heat-sealingconditions, for instance a higher temperature and/or pressure to formpermanent seal 12. Alternatively, the surface of removable reclosuremeans 14 could be coated with a heat-activated adhesive which will makeseal 12 stronger than seal 16 even if the same sealing conditions areused. On the other hand, the different bond strength can be easilyattained when rigid base member 11 and removable reclosure means 14 aremade of different materials by suitably selecting the sealing surface ofremovable reclosure means 14 to give a stronger bond with cover film 13than rigid base member 11, even at the same sealing conditions, i.e.temperature and/or pressure. Other alternative methods of forming bonds12 and 16 having different strength could be used without departing fromthe scope of the invention.

The packaging method of the invention can be performed on currentlyavailable tray lidding machines, either automatic or manual,commercially supplied by, e.g., Ross Industries, Inc., Multivac, Inc. orMondini S.p.A. with only minor modifications.

Reclosable package 10 can be opened by peeling cover film 13 open atseal 16. FIGS. 3A and 3B show reclosable package 10 in its open state:removable reclosure means 14 have been pulled from their housings 17 inbase member 11 and are integral with cover film 13. Alternatively,reclosure means can be firstly lifted from their housings 17 by pushingfrom below rigid base member and then used as a pull-tab to complete theopening of reclosable package 10. Once the consumer has removed theamount of product required, package 10 can be reclosed by insertingremovable reclosure means 14 into the complementary housings 17. Such areclosure mechanism can be used repeated times without deterioration.

The reclosable package of the invention is therefore very convenient andsimple to use. At the same time reclosable package 10 can bemanufactured with no additional separate operations with respect to aconventional non-reclosable package.

1.-10. (canceled)
 11. A reclosable package comprising: a) a rigid basemember; b) a product placed on the rigid base member; and c) a coverfilm placed over the product and sealed to the rigid base member allaround the product, characterized in that at least one removablereclosure means is embedded in the rigid base member, and the cover filmis secured to the at least one removable reclosure means.
 12. Thereclosable package according to claim 11 wherein the cover film forms apeelable seal with the rigid base member, and is permanently secured tothe at least one removable reclosure means.
 13. The reclosable packageaccording to claim 11 wherein the at least one removable reclosure meanscomprises a plurality of discrete elements.
 14. The reclosable packageaccording to claim 11 wherein the at least one removable reclosure meanscomprises one continuous frame around the product.
 15. The reclosablepackage according to claim 11 wherein the rigid base member comprises afoamed thermoplastic material selected from the group consisting ofpolystyrene, polyester and polypropylene.
 16. The reclosable packageaccording to claim 11 wherein the at least one removable reclosure meanscomprises the same material as the rigid base member.
 17. A reclosablepackage comprising: d) a rigid base member; e) a product placed on therigid base member; and f) a cover film placed over the product andsealed to the rigid base member all around the product, characterized inthat at least one removable reclosure means is partially attached to therigid base member, and the cover film is secured to the at least oneremovable reclosure means.
 18. A method for the manufacture of areclosable package comprising the steps of: a) providing a rigid basemember having at least one removable reclosure means embedded therein;b) placing a product over the rigid base member; c) laying a cover filmover the product; and d) securing the cover film to the base memberaround the product and to the at least one removable reclosure means.19. The method according to claim 18 wherein the steps of sealing thecover film to the rigid base member and securing the cover film to theat least one removable reclosure means take place simultaneously. 20.The method according to claim 18 comprising evacuating the space betweenthe rigid base member and the cover film.
 21. The method according toclaim 18 comprising gas flushing the space between the rigid base memberand the cover film with a suitable gas or gas mixture.